The numbers game
Owners have very high expectations of one’s ability to diagnose a condition based on their description, what they read on the internet, and (to a lesser extent) my physical examination. Don’t get me wrong- taking an accurate history and doing a physical examination are instrumental skills. But they are not 100%.
“What is it, doc?” the owner asks as I poke at a lump. I can give you some guesses with a good amount of accuracy based on its appearance, how it moves on or under the skin, that sort of thing. “90% of the time this sort of mass turns out to be a benign lipoma,” I might say. “But I’d still like to verify that.” 10% doesn’t seem like a lot, unless of course you are that 10%.
Koa had a mass on her shoulder that I was 90% sure was a lipoma. I performed a fine needle aspirate, which is the least invasive and most common first-line diagnostic that I use for masses under the skin. I am aware of its limitations- 25% of the time you don’t get a diagnostic sample, especially if you are dealing with the type of mass that sticks to itself tightly and doesn’t like to be sucked into a needle. Perhaps you don’t get the needle into the right portion of the mass. False negatives happen.
Koa’s aspirate was full of fat, just like your typical lipoma. So I watched it.
Last week, I revisited the mass and decided that it might be bigger. In my fingers, it behaved just like your typical lipoma- squishy, easily moving around in the subcutaneous fat without digging into the muscle beneath. But maybe it was just a teeny bit firmer than I would like? So I stuck a needle in it. Fat cells, again.
At that point, I had reached the limitations of the aspirate. I could do a more extensive biopsy, but in this case I decided to just remove the blasted thing. And guess what? It was fatty. Fatty tissue surrounding a smaller, firm, ugly ball of something decidedly not-fat.
I will let a pathologist slice it, look at it under a microscope and tell me all the things my eyes and fingers cannot: the type of cell, the margins, how likely it is to grow back. I know that many of these types of tumors can be cured with one surgery, if you happen to remove them before they do nasty invasive things.
So I wait for the results, keep my fingers crossed, and remind myself to be glad I don’t rely on numbers. After all, the median survival time for a lymphoma patient on chemo is 12 months, not two. I trust cancer not a whit.
